FILE - In this Sept. 5, 2017 file photo, a protester holds a sign at a rally at Metropolitan State University after President Donald Trump's decision to repeal a program protecting young immigrants from deportation in Denver. (AP Photo/Tatiana Flowers, File)

A new study concludes that illegal immigration is draining over $100 billion from taxpayers’ wallets every year, but some experts say the report vastly overstates the costs of government benefits used by undocumented immigrants and overlooks their families’ economic contributions.

The study by researchers Matthew O’Brien, Spencer Raley, and Jack Martin calculates that taxpayers spend a total of approximately $134.9 billion to cover the expenses produced by the presence of 12.5 million undocumented immigrants and 4.2 million U.S.-born children, while those immigrants pay about $19 billion in taxes, for a net cost of $115.9 billion. FAIR describes this figure as “staggering and crippling.”

The 2017 total represents an increase of nearly $3 billion since the group’s previous analysis in 2013, and it breaks down to about $8,000 per undocumented immigrant family member per year.

“Allowing these people to work, whether it be under the table or through fraud or people who just don’t care about the regulations, combined with all of the benefits they can collect when they’re here is a huge draw,” O’Brien, director of research at FAIR, said in an interview, “and if we don’t shut that off, then we’re going to wind up going bankrupt.”

About two-thirds of the costs tabulated by FAIR fall on the state and local governments, while the federal government spends about $45.8 billion. The services covered in these calculations include public education, medical care, justice enforcement, welfare programs, and other general expenses.

“We’re talking things like using roads, using the water system, using public utilities, going to public schools,” O’Brien said.

While undocumented immigrants are ineligible for many federal welfare benefits, the analysis takes into account that their U.S.-born children are eligible and that many states have opted to offer some benefits to those in the country illegally. Those children are U.S. citizens, but FAIR includes their costs because they would not be in the country if not for their parents’ illegal entry.

“A large number of states have decided willingly to give benefits to illegal aliens, which means that there are freebies to people who have no right to be in this country and collecting,” O’Brien said.

The authors attempt to refute some common claims by immigration advocates. While many undocumented immigrants file tax returns, for example, they maintain that since they often work low-skilled, low-wage jobs, they pay little to nothing in income taxes. In some cases, they even qualify for tax credits.

“They wind up turning a profit,” O’Brien said.

Other groups that favor stricter immigration controls have estimated similar high cost for illegal immigration. According to the Center for Immigration Studies, services and benefits for the current undocumented population will cost the government nearly $750 billion in their lifetime. The Heritage Foundation estimated that undocumented households produce an annual net fiscal loss for taxpayers of around $54.5 billion.

Based on these numbers, supporters of President Trump’s immigration policies have argued that deporting the undocumented immigrant population would pay for itself, or that the savings for taxpayers from stopping unauthorized entry would more than make up for the cost of a border wall.make up for the cost of a border wall.

“Essentially, we’re paying people to be here unlawfully present in the United States, which is insane when you stop to think about it,” O’Brien said.

Other immigration experts take issue with FAIR’s methodology and its conclusions.

Alex Nowrasteh, an immigration policy analyst at the libertarian Cato Institute, called the study “fatally flawed,” arguing that using what he considers more accurate data would reduce the cost to somewhere between $3.3 billion and $15.6 billion. He emphasized that he is not saying that is the correct cost but merely what the same controversial methods would estimate with better raw data.

Nowrasteh questioned the underlying figure of 12.5 million undocumented immigrants, 1.5 million more than many other organizations and even 1 million more than the ideologically similar Center for Immigration Studies. He calculated that using 11 million instead would reduce the total by $11.6 billion.

In a blog post Friday, Walter Ewing, a senior researcher at the American Immigration Council, expressed similar concerns about FAIR’s analysis.

“This is a baseless argument that FAIR makes repeatedly, and it rests upon a number of flawed assumptions about the impact that undocumented immigrants and their children have on the U.S. economy,” he wrote.

O’Brien and Raley said Friday that their critics are the ones using the wrong numbers.

Detractors also questioned why the study includes the welfare services provided to children of undocumented immigrants but does not also account for the tax revenue they will eventually produce when they get jobs.

“FAIR makes an unfair point,” Nowrasteh said Friday. “If you count the costs, then you must count the benefits, including the benefits of the adult children of illegal immigrants born in the United States.”

According to O’Brien and Raley, the “presumptive possible fiscal return in the future” is unrelated to their estimate of what the undocumented immigrant population costs today.

“From a statistical standpoint, we’re looking at the cost as it stands right now,” Raley said.

O’Brien also questioned whether including such data would really balance the scales.

“Most of these children are not going to have a working life long enough to pay for the services they consumed,” he said.

Ewing acknowledged that FAIR’s research does not purport to be more than an analysis of current costs, but he questioned the value of that figure for the broader immigration debate.

“My argument is that a study like that is inherently biased because it doesn't count lifetime costs and benefits,” he said via email Friday. “A snapshot can't give you that kind of information--and that's what you need to know to gauge the economic impact of immigration.”

The FAIR study estimates federal immigration enforcement costs at $13.1 billion, but Nowrasteh said it is “silly” to count the cost of enforcement against the immigrants when you could just cut enforcement spending, except for the $1.24 billion spent on incarceration of those convicted of other crimes.

“That’s sort of like saying if you were to make theft legal, you wouldn’t have to pay for enforcement of that,” O’Brien said.

“The question is, is that good for society and does that protect us?” he asked.

Nowrasteh cited a 2005 study based on 1998 data that concluded per capita health care expenditures for immigrants were 55 percent lower than for U.S.-born patients, extrapolating that this would equate to $13.9 billion less than FAIR estimated for health care services for undocumented immigrants.

O’Brien and Raley disputed the accuracy of that figure and also noted that undocumented immigrants may rely more on expensive emergency room care than regular doctors, driving up their costs. Even if the 55 percent estimate is outdated, Nowrasteh said numerous other studies also found immigrants use less health care spending than native patients.

He also alleged that the study underestimated Social Security and Medicare tax contributions from wages and sales tax revenue from purchases by undocumented immigrants, and he pointed to research indicating that the presence of immigrants in a community boosts property tax revenues.

Nowrasteh suggested the biggest methodological error was not factoring in a predicted loss in economic activity and tax revenue if millions of undocumented workers were gone, leaving a “gaping economic hole.”

However, the study’s authors believe that hole is vastly inflated because it presumes those jobs would not be filled by native workers or by innovation and automation that would contribute to economic growth. According to Raley, states that have implemented E-verify to make it harder to hire undocumented immigrants have seen a drop in unemployment.

“You could certainly replace that productivity with American workers,” O’Brien said, and those workers would likely need to be paid more, leading to higher income tax revenues.

Despite the questions raised by other experts, the authors of the FAIR study stand by their findings.

“It’s very easy for people on the other side of this issue to pick this apart and focus on the nitty-gritty, but this is really an exercise in looking at the totality,” O’Brien said, “and if anything, the estimates are probably lower than they should be.”